Are you using Sketch Plus?
If so, upgrade to v1.3x and you can set different feed rates for raster and vector which should have the same result. It would actually be faster as you can use full power for the engraving with a much higher feed rate.
It's not a bad idea to have a separate laser power option for vector vs. raster, the same as I have for feed rate so I will add that to my "wish list".
Regarding the manual editing, just search for g-code commands and you'll see several sites. Grbl uses a subset, but most of the common commands are supported. The main ones that aren't are related to canned cycles or sub routines.